Compressor pistons and compressors including such pistons

ABSTRACT

A compressor may include a cylinder block having a plurality of cylinder bores formed therethrough, a drive shaft rotatably supported by the cylinder block, and a swash plate rotatably mounted on said drive shaft. The compressor also may include a plurality of pistons, and each of the cylinder bores may have an outer radial edge. Moreover, each of the pistons may include a head portion which is slidably inserted inside one of the cylinder bores, and a skirt portion which extends from an end surface of the head portion, in which the skirt portion includes a pair of shoe receiving portions. Each piston also may include a rotation prevention portion which is formed at the skirt portion and prevents the piston from rotating about its axis. Moreover, a first separation distance between an axis of rotation of the swash plate and an abutment portion of the rotation prevention portion which slidably abuts an interior wall of a compressor housing is less than a second separation distance between the axis of rotation of the swash plate and a portion of the outer radial edge which edge is furthest from the axis of rotation of the swash plate.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates generally to compressor pistons and compressors including such pistons. More particularly, the invention relates to pistons for use in swash plate-type compressors.

[0003] 2. Description of Related Art

[0004] Referring to FIG. 1, known compressors may comprise a plurality of pistons 1, and each piston 1 may comprise a head portion 2 and a skirt portion 3. Head portion 2 may be slidably inserted inside a cylinder bore of such known compressors, and the cylinder bore may include an outer radial edge. Skirt portion 3 may comprise a pair of shoe receiving portions 6, and may be coupled to a swash plate 5 via a pair of shoes positioned within shoes receiving portions 6. In operation, when a drive shaft of the known compressor is rotated, swash plate 5 may rotate about an axis X, and pistons 1 may reciprocate within their corresponding cylinder bore. Moreover, each skirt portion 3 may comprise a pair of rotation prevention portions 4 a and 4 b, which prevent their corresponding piston 1 from rotating about its axis, when piston 1 reciprocates within the cylinder bore. Specifically, rotation prevention portions 4 a and 4 b contact an interior wall of a compressor housing in order to prevent piston 1 from rotating about its axis.

[0005] Nevertheless, in such known compressors, a first separation distance R1 between axis X of swash plate 5 and rotation prevention portions 4 a and 4 b is greater than a second separation distance R2 between axis X and a portion of the outer radial edge of the cylinder bore, which edge is furthest from axis X. As such, R1 is greater than a radius of an arc C which includes a portion of the outer radial edge of the cylinder bore, which edge is furthest from axis X. Consequently, a size of the compressor housing may increase.

SUMMARY OF THE INVENTION

[0006] Therefore, a need has arisen for pistons and compressors including such compressors, which overcome these and other shortcomings of the related art. A technical advantage of the present invention is that a distance between an axis of rotation of a swash plate and an abutment portion of a piston may be less than a distance between the axis of rotation of the swash plate and a portion of a cylinder bore's outer radial edge which is furthest from the axis of rotation of the swash plate. Consequently, a size of a compressor housing may be reduced relative to such known compressors.

[0007] According to an embodiment of the present invention, a piston for use in a compressor is described. The piston comprises a head portion which is slidably inserted inside a cylinder bore, and the cylinder bore has an outer radial edge. The piston also comprises a skirt portion which extends from an end surface of the head portion, and the skirt portion comprises a pair of shoe receiving portions. The piston further comprises a rotation prevention portion which is formed at the skirt portion and prevents the piston from rotating about its axis. Moreover, a first separation distance between an axis of rotation of a swash plate and an abutment portion of the rotation prevention portion which, slidably abuts an interior wall of a compressor housing, is less than a second separation distance between the axis of rotation of the swash plate and a portion of the outer radial edge which edge is furthest from the axis of rotation of the swash plate.

[0008] According to another embodiment of the present invention, a piston for use in a compressor is described. The piston comprises a head portion which is slidably inserted inside a cylinder bore, and the cylinder bore has an outer radial edge. The piston also comprises a skirt portion which extends from an end surface of the head portion, and the skirt portion comprises a pair of shoe receiving portions. The piston further comprises a rotation prevention portion which is formed at the skirt portion and prevents the piston from rotating about its axis. Moreover, a separation distance between an axis of rotation of a swash plate and an abutment portion of the rotation prevention portion, which slidably abuts an interior wall of a compressor housing, is less than a radius of an arc which includes a portion of the outer radial edge which edge is furthest from the axis of rotation of the swash plate.

[0009] According to yet another embodiment of the present invention, a compressor is described. The compressor comprises a cylinder block having a plurality of cylinder bores formed therethrough, a drive shaft rotatably supported by the cylinder block, and a swash plate rotatably mounted on said drive shaft. The compressor also may comprise a plurality of pistons, and each of the cylinder bores may have an outer radial edge. Moreover, each of the pistons may comprise a head portion which is slidably inserted inside one of the cylinder bores, and a skirt portion which extends from an end surface of the head portion, in which the skirt portion comprises a pair of shoe receiving portions. Each of the pistons also may comprise a rotation prevention portion which is formed at the skirt portion and prevents the piston from rotating about its axis. Moreover, a first separation distance between an axis of rotation of the swash plate and an abutment portion of the rotation prevention portion, which slidably abuts an interior wall of a compressor housing, is less than a second separation distance between the axis of rotation of the swash plate and a portion of the outer radial edge which edge is furthest from the axis of rotation of the swash plate.

[0010] According to still another embodiment of the present invention, a compressor is described. The compressor comprises a cylinder block having a plurality of cylinder bores formed therethrough, a drive shaft rotatably supported by the cylinder block, and a swash plate rotatably mounted on said drive shaft. The compressor also may comprise a plurality of pistons, and each of the cylinder bores may have an outer radial edge. Moreover, each of the pistons may comprise a head portion which is slidably inserted inside one of the cylinder bores, and a skirt portion which extends from an end surface of the head portion, in which the skirt portion comprises a pair of shoe receiving portions. Each of the pistons also may comprise a rotation prevention portion which is formed at the skirt portion and prevents the piston from rotating about its axis. Moreover, a separation distance between an axis of rotation of the swash plate and an abutment portion of the rotation prevention portion, which slidably abuts an interior wall of a compressor housing, is less than a radius of an arc which includes a portion of the outer radial edge which edge is furthest from the axis of rotation of the swash plate.

[0011] Other objects, features, and advantages of the present invention will be apparent to persons of ordinary skill in the art in view of the foregoing detailed description of the invention and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] For a more complete understanding of the present invention, needs satisfied thereby, and the objects, features, and advantages thereof, reference now is made to the following description taken in connection with the accompanying drawings.

[0013]FIG. 1 is a cutaway perspective view of a known piston for use in a swash plate-type compressor.

[0014]FIG. 2 is a partial, cutaway cross-sectional view of a compressor including a piston, according to an embodiment of the present invention.

[0015]FIG. 3a is a plan view of the compressor piston of FIG. 2, according to an embodiment of the present invention.

[0016]FIG. 3b is a partial side view of the compressor piston of FIG. 2, according to an embodiment of the present invention.

[0017]FIG. 3c is a front view of the compressor piston of FIG. 2, according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

[0018] Preferred embodiments of the present invention and their advantages may be understood by referring to FIGS. 2-3 c, like numerals being used for corresponding parts in the various drawings.

[0019] Referring to FIGS. 2-3 c, a piston 10 for use in a compressor, e.g., a swash plate-type compressor, and a compressor 100 employing piston 10, are described. Compressor 100 may include a compressor housing H, a swash plate P, and a pair of shoes S. Compressor 100 also may comprise a plurality of pistons 10, and each piston 10 may comprise a head portion 11 and a skirt portion 12. In an embodiment of the present invention, head portion 11 may have a cylindrical shape. Head portion 2 may be inserted slidably inside a cylinder bore of the known compressor, and the cylinder bore may include an outer radial edge E. Skirt portion 12 may comprise a pair of shoe receiving portions 13 a and 13 b, and may be coupled to swash plate P via shoes S which are positioned within shoes receiving portions 13 a and 13 b, respectively. In operation, when a drive shaft of compressor 100 is rotated, swash plate P may rotate about an axis Y, and pistons 10 may reciprocate within their corresponding cylinder bore. Moreover, each skirt portion 12 may comprise a pair of rotation prevention portions 12 a and 12 b which prevent their corresponding piston 10 from rotating about its axis when piston 10 reciprocates within the cylinder bore. Specifically, rotation prevention portions 12 a and 12 b contact an interior wall of compressor housing H in order to prevent piston 10 from rotating about its axis.

[0020] In an embodiment of the present invention, a first separation distance R11 between axis X of swash plate P and rotation prevention portions 12 a and 12 b may be less than a second separation distance R12 between axis X and a portion of outer radial edge E which is furthest from axis X. As such, R11 may be less than a radius of an arc G which includes a portion of outer radial edge E which is furthest from axis Y. Consequently, a size of compressor housing H may be reduced.

[0021] In another embodiment of the present invention, projection portions 12 a and 12 b may have a curved surface α, and projection portions 12 a and 12 b may be connected to shoe receiving portions 13 a and 13 b, respectively, at curved surface α. Curved surface α may include a pair of concave surfaces and a convex surface positioned between the concave surfaces. Moreover, when swash plate P moves and a moment of inertia is applied to curved surface α, the moment of inertia more readily may be dispersed because of the curved shaped of surface α. Further, a weight of piston 10 may be reduced.

[0022] While the invention has been described in connecting with preferred embodiments, it will be understood by those of ordinary skill in the art that other variations and modifications of the preferred embodiments described above may be made without departing from the scope of the invention. Other embodiments will be apparent to those of ordinary skill in the art from a consideration of the specification or practice of the invention disclosed herein. It is intended that the specification and the described examples are considered as exemplary only, with the true scope and spirit of the invention indicated by the following claims. 

What is claimed is:
 1. A piston for use in a compressor, comprising: a head portion which is slidably inserted inside a cylinder bore, wherein the cylinder bore has an outer radial edge; a skirt portion which extends from an end surface of the head portion, and comprises a pair of shoe receiving portions; and a rotation prevention portion which is formed at the skirt portion and prevents the piston from rotating about its axis, wherein a first separation distance between an axis of rotation of a swash plate and an abutment portion of the rotation prevention portion which slidably abuts an interior wall of a compressor housing is less than a second separation distance between the axis of rotation of the swash plate and a portion of the outer radial edge which edge is furthest from the axis of rotation of the swash plate.
 2. The piston of claim 1, wherein said abutment portion has a pair of projection portions extending from said shoe receiving portion.
 3. The piston of claim 2, wherein the projection portions comprise a curved surface.
 4. The piston of claim 3, wherein the curved surface comprises a pair of concave portions, and a convex portion which is positioned between the concave portions.
 5. A compressor, comprising: a cylinder block having a plurality of cylinder bores formed therethrough, wherein each of the cylinder bores has an outer edge; a drive shaft rotatably supported by the cylinder block; a swash plate rotatably mounted on said drive shaft; and a plurality of pistons, wherein each of the pistons comprise: a head portion which is slidably inserted inside one of the cylinder bores; a skirt portion which extends from an end surface of the head portion, and comprises a pair of shoe receiving portions; and a rotation prevention portion which is formed at the skirt portion and prevents the piston from rotating about its axis, wherein a first separation distance between an axis of rotation of the swash plate and an abutment portion of the rotation prevention portion which slidably abuts an interior wall of a compressor housing is less than a second separation distance between the axis of rotation of the swash plate and a portion of the outer radial edge which edge is furthest from the axis of rotation of the swash plate.
 6. The compressor of claim 5, wherein said abutment portion has a pair of projection portions extending from said shoe receiving portion.
 7. The compressor of claim 6, wherein the projection portions comprise a curved surface.
 8. The compressor of claim 7, wherein the curved surface comprises a pair of concave portions, and a convex portion which is positioned between the concave portions.
 9. A piston for use in a compressor, comprising: a head portion which is slidably inserted inside a cylinder bore, wherein the cylinder bore has an outer radial edge; a skirt portion which extends from an end surface of the head portion, and comprises a pair of shoe receiving portions; and a rotation prevention portion which is formed at the skirt portion and prevents the piston from rotating about its axis, wherein a separation distance between an axis of rotation of a swash plate and an abutment portion of the rotation prevention portion which slidably abuts an interior wall of a compressor housing is less than a radius of an arc which includes a portion of the outer radial edge which edge is furthest from the axis of rotation of the swash plate.
 10. The piston of claim 9, wherein said abutment portion has a pair of projection portions extending from said shoe receiving portion.
 11. The piston of claim 10, wherein the projection portions comprise a curved surface.
 12. The piston of claim 11, wherein the curved surface comprises a pair of concave portions, and a convex portion which is positioned between the concave portions.
 13. A compressor, comprising: a cylinder block having a plurality of cylinder bores formed therethrough, wherein each of the cylinder bores has an outer edge; a drive shaft rotatably supported by the cylinder block; a swash plate rotatably mounted on said drive shaft; and a plurality of pistons, wherein each of the pistons comprise: a head portion which is slidably inserted inside one of the cylinder bores, wherein each of the cylinder bores has an outer radial edge; a skirt portion which extends from an end surface of the head portion, and comprises a pair of shoe receiving portions; and a rotation prevention portion which is formed at the skirt portion and prevents the piston from rotating about its axis, wherein a separation distance between an axis of rotation of a swash plate and an abutment portion of the rotation prevention portion which slidably abuts an interior wall of a compressor housing is less than a radius of an arc which includes a portion of the outer radial edge which is furthest from the axis of rotation of the swash plate.
 14. The compressor of claim 13, wherein said abutment portion has a pair of projection portions extending from said shoe receiving portion.
 15. The compressor of claim 14, wherein the projection portions comprise a curved surface.
 16. The compressor of claim 15, wherein the curved surface comprises a pair of concave portions, and a convex portion which is positioned between the concave portions. 